Coleraine dropped two points behind leaders Cliftonville as Andy McGrory hit an injury-time Glenavon equaliser in the Premiership clash at Mourneview.
Stephen Lowry looked to have earned the Bannsiders a deserved win as he scored a superb 86th-minute goal.
Curtis Allen wasted a first-half chance and also had an effort disallowed.
Allen then failed to find an unmarked Paul Owens after an Eddie McCallion backpass while Coleraine debutant Joel Bradley had another effort ruled out.
The Bannsiders had dominated possession in the second half although Glenavon deserve credit for battling right until the end.
Allen wasted the best first-half chance as he blasted over on 19 minutes after the Glenavon defence had been carved open.
Good work by Allen then looked likely to set up a chance for 17-year-old Bradley but Marc Brown got back to make a last-ditch clearance.
Allen did have the ball in the Glenavon effort before the break but it was ruled out for offside.
McCallion's dreadful backpass gifted a glorious chance to the Bannsiders but Allen attempted to go for goal himself instead of finding unmarked colleague Owens.
Coleraine had another goal disallowed for offside after Bradley had rounded Andy Coleman.
However, the Bannsiders' frustrations appeared to have been eased four minutes from time after Lowry jinked past three challenges before hammering a glorious goal past the Glenavon keeper.
But Glenavon, to their credit, kept battling and substitute McGrory stabbed home from close range in the third minute of injury-time after a corner.